Waveshare Audio Driver HAT REV2

Product Overview

The Audio Driver HAT REV2, produced by Waveshare Electronics, is an audio expansion board featuring the ES7210+ES8156 dual Codec solution. It supports 4-channel circular microphone recording, dual-channel audio playback, audio loopback, and more. The board is shown below:

For detailed information about the audio sub-board, please refer to the Audio Driver HAT.

Installation

• Hardware Setup

1. Connect the expansion board to the 40-pin header of the RDK X3 as shown below.
   

2. Set all 3 DIP switches to the OFF position.

• Software Configuration

1. Use srpi-config to configure the audio board.
   Go to 3 Interface Options -> I5 Audio
   Select Audio Driver HAT V2:

2. Follow the prompts to execute the reboot command, or run sync && reboot to restart the board. If cat /proc/asound/cards shows a sound card other than duplexaudio, the expansion board is installed successfully.

root@ubuntu:~# cat /proc/asound/cards 
 0 [duplexaudioi2s1]: simple-card - duplex-audio-i2s1
                      duplex-audio-i2s1
 1 [duplexaudio    ]: simple-card - duplex-audio
                      duplex-audio

• Uninstallation

1. Use srpi-config to configure the audio board.
   Go to 3 Interface Options -> I5 Audio
   Select UNSET to uninstall the audio driver and related configurations.

2. Remove the expansion board.

Usage

Check if the sound card exists and verify the device number.

To confirm the sound card is registered (as mentioned above):

root@ubuntu:~# cat /proc/asound/cards 
 0 [duplexaudioi2s1]: simple-card - duplex-audio-i2s1
                      duplex-audio-i2s1
 1 [duplexaudio    ]: simple-card - duplex-audio
                      duplex-audio

Confirm the logical device by using the command cat /proc/asound/devices:

root@ubuntu:~# cat /proc/asound/devices
  2: [ 0- 0]: digital audio playback
  3: [ 0- 1]: digital audio capture
  4: [ 0]   : control
  5: [ 1- 0]: digital audio playback
  6: [ 1- 0]: digital audio capture
  7: [ 1]   : control
 33:        : timer

Check the actual device files in user space through the ls /dev/snd/ command:

root@ubuntu:~# ls /dev/snd/
by-path  controlC0  controlC1  pcmC0D0p  pcmC0D1c  pcmC1D0c  pcmC1D0p  timer

From the above, and with reference to the Onboard Earphone Audio Port, you can confirm that sound card 0 corresponds to the Audio Driver HAT REV2 node; the devices exist, and the device numbers are 0-0 and 0-1. The actual devices to operate are pcmC0D0p and pcmC0D1c.

The onboard sound card corresponds to 1, with device number 1-0, which is not used here.

• Recording

• 2-channel microphone recording:

tinycap ./2chn_test.wav -D 0 -d 1 -c 2 -b 16 -r 48000 -p 512 -n 4 -t 5

• 4-channel microphone recording:

tinycap ./4chn_test.wav -D 0 -d 1 -c 4 -b 16 -r 48000 -p 512 -n 4 -t 5

• Playback

• Dual-channel audio playback (4-channel playback is not supported):

tinyplay ./2chn_test.wav -D 0 -d 0

Audio Loopback Test

The audio loopback function can be used to capture signals from the playback channel for subsequent analysis.

• 8-Channel Microphone Recording (Including Loopback)
  The loopback signal on this audio board is mapped to recording channels 7 and 8. Use the 8-channel recording command:

  tinycap ./8chn_test.wav -D 0 -d 1 -c 8 -b 16 -r 48000 -p 512 -n 4 -t 5

• Simultaneously Start Dual-Channel Audio Playback

  tinyplay ./2chn_test.wav -D 0 -d 0

• Analyze the Loopback Signal
  After recording, use audio analysis software such as Audacity to open 8chn_test.wav and examine the waveform or spectrum of channels 7 and 8 to verify whether the loopback function is working correctly.

FAQ

• If no sound card is detected, check whether the hardware connections and DIP switch settings are correct.

• If there is no sound during recording or playback, confirm that the audio file format and channel count match the command parameters.

• If there is no signal in the loopback channel, ensure that the 8-channel recording command has been used correctly. For more questions, see this link